Aeroplane.



J. W. DUNNE.

AEBOPLANB. APPLICATION rum) 1211.1. 1910.

1 ,0O3,'721 Patented Sept. 19, 1911.

9 SHEETS-SHEET 1.

Y Y Y1 J. w. DUNNB. AEEOPLANE.

APPLIOATIOH FILED APR. 1, 1810.

0 3 721 Patented Sept. 19, 1911.

9 BIiEHTB-BHEBT 2.

Fig. 5.

Atty

J. W. DUNNE.

AEROPLANE.

APPLICATION FILED APRJ, 1910.

1,003,721. 1 Patented Sept. 19,1911.

9 SHEETS-SHEET 4.

7 QM 424N441 J. W. DUNNB.

AEROPLANE.

APPLICATION FILED 3.1. 1010.

1,003,721. Patented Sept.,19,191 1.

9 SHEETS-SHEET 5.

YYBY? Y Y m J. W. DUNNE.

ABROPLANE.

APILIOATION FILED 11.1, 1010.

9 BHBETS'BHEBT 6,

1,003,721. Patented Sept. 19, 1911.

Wziu, asses.

I14. vg uf ymay J. W. DUNNE. ABBOPLANE.

APPLICATION mum APB.1,, 1910.

1,003,721. Patented Sept. 19,1911.

9 SHEETS-SHEET 9.

wl iwas ses;

arranged that the UNITED STATES PATENT OFFICE.

- WILLIAM DUNNE, OF LONDON, ENGLAND, ASSIGNOR T0 DLAIR ATHOLL AEBOPLANE SYNDICATE LIMITED, OF LONDON, ENGLAND.

AEROPLANE.

Specification of Letters Patent.

Patented Sept. 19, 1911.

Application filed April 1, 1910. Serial No. 552,833.

To all whom it may concern:

Be it known that I, JOHN OWILLIAM D NNE, a subject of the King of Great Britain and Ireland, and residin at 16 'Charing Cross, London W. C., fingland, have invented certain new and useful Improvemnts Relating to Aeroplanes', of which the following is a specification.

The object of the present invention is to obtain a form of aeroplane which by virtue solely of the arrangement and form of its supporting surfaces possesses when properly ballasted automatic stability in still air, and also, without requiring any alteration of its center of gravity or of its surfaces, in very high winds; further, to construct the aero.- plane in such a manner that it possesses in calm and in agitated air a large measure of "freedom from oscillation, a quality quite distinct from that 'of stable equilibrium, and also to obtain large pressure reactions when the aeroplane is driven at an angle against the air. a

'The invention consists in constructing each of the main supporting surfaces as a rearwardly projecting rigid wing, the angle of incidence of which decreases from the center toward the tips and in some cases changes sign and compensating for the decreased lifting power of the tips by shaping the wing so as to compress air between a positively inclined portion of the wing near the center and a negatively inclined portion in the region of the tip.

The invention also consists in constructing each of the main support-mg surfaces as a rearwardly projecting wing, the upper face of which may be defined as traced by a straight line traveling on two guide curves one of'which may be infinitely small, 'so resulting surface swept out is convex toward its upper side in all sections taken fore and aft and laterally, 'theangle of incidence gradually decreasing from the center to the ends of the wings and in some cases'changing sign, and the lower faces of the wings being preferably concave.

The invention also consists in constructing eachof the superposed main supportlng surfaces of a biplane, for example, as a projecting wing, the angles of incidence of the "'uppermost surfaces gradually decreasingtowardthe tips and in some cases changing sign while the decrease s so arranged that the tips of the uppermost wings are inclined downward and forward in relation to the tips of preferably the lowermost pair.

The invention also consists in the improved constructions of aeroplane hereinafter described.

It will be understood that in the present specification, where not otherwise specified, the surfaces of the wings referred to are the upper surfaces, the lower surfaces being preferably concave, although plane or even convex portions may occur where such are advisable by reason of considerations such as the strength of the structure. It will also be understood that the expression angle of incidence in the fore and aft direction means in the case of a plane surface the angle made by the fore and aft section of that surface with the line of flight; in the case of a curved surface the angle made by the line of flight with a straight line drawn from front end to rear end of the curve exposed by a cross section. I

In order to. obtain large pressure reac tions when the aeroplane is'driven at an angle against the air the lifting surfaces must be convex on the upper side and preferably concave on the under side. Further, the machine should be supported by either a single pair of main wings, one wing on each side, or by two such systems placed one above the other as the addition of any further surfacestends to reduce the efficiency of the whole.

In order to maintain fore and aft stability, I have found it advisable that the whole or'the outer part of each wing should have'its leading edge so sloped backward and outward that the tips of the wings come behind the center of gravity of the appa-- ratus.

I find that in plan the angle of inclination of the wings to the line of flight is preferably between the limits of 40 and 70.

In order to render the machine free from oscillation, it is advisable that as the wing extends outward the angle of incidence should decrease gradually so that there may be noabrupt alteration of angle at any part of the wing. \Vith a wing so formed alterations of the mean angle of incidence bring into play gradual alterations in the pressures on the wings gently to correct the "deviation from normal conditions. It is of the great- ,tween the angles of incidence. of the inner. and outer portions of the wing should be,

the normal-conditions increases.

est importance that this correction shohld be gentle at the commencement of an oscillation, audit is equally important that the tendency should persist through" wide ranges of variation-in the mean angle of incidence am-11d increase as the departure from i This latter condition'requ'ires that the difference, be-

- considerable, a condition which in turn requires n general-a'negati-ve angle of incidence at the tips under normal: flight ,con-- ditions.

I have found that .twist-ing the wings or rendering them-fie'xible so'that they twist under-air pressure, to cause the tips to present the requisite small angle, involves the 'disa dmntage that-sections taken fore and aft across theztips of the wings or from the 'inner'portion to the tip give curves more or 1 less concave on their upper sides, thus greatly detracting from the lifting powers of the wing. twisted wing therefore'is unableto give large pressure reaction when driven at an angle against the air. I have found furthen that when such a twistedwing changes its mean .angle of incidence the changes thereby brought-about in the pressures on the outer portions which are concave on their upper sides occur far too abruptly for steadiness, andin very high winds znav produce a condition of unstable equilibrium. Also that the similar concavity on thelater-al cross section of the wings gives lateral instability in disturbed air. vThis form of wing therefore-isnotsuitable. In order to obtain the correct form therefore it is neces sary to considers Firstly, how the-angle of the fore and aft sections can be made grad :ually to decrease as the wing-is built outward without'producing points of inflection in thesurfaces; and secondly, how consid= erable difi'erences in the angles of the inner and outer portions can be maintained with out .too inuchloss of pressure under-the outer portions and therefore loss' of lifting power.

I will now describe certain forms of surface byway of examplewh-ich meet-the conditions laid down above and "will then describe examples of complete aeroplanes v in whichone such wing form is embodied.

' Referringfor this purpose to the accompanying drawings which form partot the specificat-ion:.-Figure 1 shows a plan of a l form of wing inwhich the upper face forms partof a conical surface with rearwardly disposed apex; Fig. 2 beinga corresponding side 'elevat-ion; Fig; 3 showsa plan of anpther modification. in which the upper face of the wing forms part of a conical surface-with 'forwardly disposed apex, land 5 being corresponding rear View and side elevations;' Fig. G'shows a plan of a and travels along the guide curve guide curve referred to above may eith er tion taken through the conesurfaceffbi nied' 5 modified form of wing in which the upper t'aceis composed of parts of two conical surfaces with reversely. disposed spices Fig. 7

being a corresponding side elevation Fig.

8 shows a plan of another modification of wing in which theupper face 1s composed partly of a conipal surfac'e'withia forwardly disposed apex. and partly of a3 cylindrical surface, Figs/9 and 10- being corresponding rear and side elevations respectiv'ely;-white 5 Fig. 11 shows .a" plan of a modification in Willfill the upper face of the" Wing forms part: of a cylindrical surface, Fig. 12 being H a corresponding side elevation. In the above plan views the left-hand wing only is shown 89 for-simplicity in each case, the right ha'ndwing being understood to be similar and symmetrically situated with regard thereto. on the other side-of the center line, the position. of which is indicated by the arrow; the arrow likewise shows the direction'of flight; Moreover, those parts of the wing outline i which are hidden are dotted in'theifigures while such parts of the guidecurves' as do not coincide with the wing out-line are indi-- cated by dot-and-dash lines. Fig. 13 shows a plan of a-nlonoplane in-which is embodied the wing form of Fig. 1. Figs, 14 and'l5 being corresponding side and front eleva-- t-ions; while Fig. 16 shows a perspective View I of the frame. supporting the propellers. Fig.1? shows a plan of a biplane embodying my improvements. Figs. 18, and 19 being corresponding rear and side elevations; Figs. 20, 21 and 22 show plan, rear and side ele- 'vations of one of the upper wings, while Figs. 23 and 2-1 show rear and side elevations respectively of acorresponding lower wing,

the plan view of which is the same as that shown in F 1g. 4.

I wish it to'be understood that the drawings are to a certain extent of a diagrarnmatic nature, the control gear and certain of the usual ties, for example, being omitted in the general views in order. to avoid undue 11(3 I reuse e considered as infinitely small and at Xi, or it inay'for facility in constr dtrh be the curve exposed by any conveni entiih y the n X Y I is It will'be seen on reference to Fig the principal guide curve, E C, is straight between the points, F and D, so that the portion of the wing surface inclosed within the figure A H D G, (Fig. 1) is a plane. For the sake of clearness in this part of the description the wing may be considered to have no thickness so that the straight line, X Y sweeps out at the same time a wing surface which isconcave below and convex above. Further, by selecting that portionv of the conical surface so generated indicated by the parallelogram, A B C D,,the angles of incidence of the fore and aft section of such wing gradually become less and change sign as the wing is built outward. It will be evident therefore that this form of wing fulfils one of the necessary conditions of the problem. Again, when a wing of the form described is driven against the air at a small mean angle of incidence, the airowing to the larger-angle of incidence of the inner and forward portions of the wing 'is driven slightly outward as well as downward, thus transmitting pressure across the underside of the wing on to the down-turned under surface of. the negatively inclined tips and so compensating tofa considerable extent for the imperfect air supply from the normal front direction due to the small or negative angle of inclination. Again, it will be seen that the whole of the under surface of the -throughthe line, F G, for example.

wing may be considered as forming a channel the trend or axis of which is toward the apex of the cone. There is a tendency therefore not only to force the air outward along these channels or pipes but also to compress it thereby increasing the pressure under the outer portions, and thus adding further to the lift under these portions. The feed of air from the inner or forward portions toward the outer portions and the compression of air under the outer portions enables the outer portions to be placed at a very considerable negative angle of incidence as compared with the inner portions without incurring serious loss of lifting power. Such a form of wing therefore completely solves the problem, and is the form which ,I prefer to use.

vention (see Figs'. 3, 4 and 5), the tracin line is pivoted at the forwardly disposed Joint, A, and travels on the guide curve, 1 D, taking up the successive positions, A X A X.,, A X and so on to A X thereby forming a cone-shaped surface. The second guide curve may in this case be considered as that exposed by a section In this form lifting power. is sacrificed to, a certain extent to increased steadiness. Such cylindrical. or conical surfaces may be described generically as develo aide. Further, he-

tween'the two forms 0 the invention above described, intermediate forms may be employed in which the generating line on the whole moves more nearly parallel to itself, such intermediate forms. permitting different degrees of'stabil-ity and liftin power to be obtained. Thus, referrin to *igs. 6 and 7, it will be seen that the outline of the wing in plan and the'guide curve, E C, are the same as in Fig. 1. The line, X Y travels.

as in Fig. 1 until it reaches the position,

X, Y,,, but then pivots about the point, A, and the X end of the line moves forward so that the line travelson the remainder of the guide curve, F C, takin u the successive positions, A X A X .4. 12,, and so on to A X,,. The wing surface thus formed consists of two cone-shaped surfaces merging into each other, one having its apex rearwardly disposed at X,, and the other having its apex oppositely disposed in a forward direction at A, butit will be seen that the natuie of the guide curve and of the travel of the line is carefully adjusted so that no inflection of the wing surface takes place at the junction of the two cone-shaped surfaces. The nature of the surface produced is very similar to that seen in Fig. 2, with the main difference, however, that the front edge is now straight. The curve exposed by any convenient section through the surface may for facility in construction be utilized as the second guide curve. I considerthat this type of wing givesmuch greater steadiness in flight than that shown in Figs. 1 and 2, but that its efficiency is less.'

Again, Figs. 8, 9 and 10, show another modification of wing surface, partly conical and partly cylindrical. The front part of the wing 1s formed as in Fig. 6, as although a different guide curve, E B, is used, the

part of this curve, E G, used in describing the surface between A G and A D is merely that exposed by a cross section taken in a similar direction through the wing shown in Fig. 6. The guide curve, however, isthen straight as far as the point, H, whence it curves downward to B and over this portion of the curve the line travels parallel to itself forminga portion of the surface of a cylinder. Two guide curves are evidently necessary for the tracing out of this part of the wing surface, and the second guide curve is indicated' by J K, the portion, L K, being a facsimile of the curve, H B. In'plan-the win is the same shape as already described wit reference to Figs.

1- and 6. This form of wing as will be explained hereinafter is well adapted for biplane construction. Finally, in thewing shown in Figs. 11 and 12, the apex or apices ofthe cone or cones of which this wing forms part of the surface or surfaces is or are removed to an infinite distance either-in the direction, X or in the direction, Y,, so that. the wing really forms part of the surface of a cylinder. The guide curves are v This enables the' builder'to one or. two fixed'patternsof rib throughout, instead of- 10.

I indicated by F B and C E. A convenience which. resultsflfroma wing of this form is that ifthe guide curves, F B and C E, be

made arcs of circles ofequal- -radius the curves exposed by any number ofparallelv planes intersecting the through both front and-back edges are'equal and, similar.

plan inlay take otherv forms than'th'e par allelogramsand triangle, shown above by.

I .way of example.

In the-above description of difierent' forms -"I' have considered the supporting surfaces to of negligible thickness, but

. it willbe evident thatin actual practice a'.

certain, thickness of the wings is necessary, The most important consideration however, is the. 'smoothness:-andsurface, as'itxis on-the perfection of 2 'partthat the steadiness ofthe machine in I where the load'is carried and lightly con-. -In constructing the wings in practice, the lower surface is preferably swept out in a positions of.-th e' cone apices, however, are different, as otherwise the .thoseof the, upper surface.

flight g ly depends. 1

similar manner to the 1 upper surface. The

edges of the under surface'gwould not approximate to v In a double surface wing, therefore, I prefer to trace the upper surface as above described, and to describe the lower surface in a similar fashion, forming the lower surface being so chosen that the frontand rearedges come as close as possible'to those of the upper surface.

vOne or. both the surfaces is or are then easedofl, until the edges are made to correspond, the alterations beingso made that thicker parts of the wing.

properly shaped ribs.

smoothness and regularity are preserved as much as' possible. Itmay, visable in some cases. to. subordinate the regular coning of the under surface to cohsiderations of the best position for the amachine on this principle, the upper surface would be properly swept out by the straight line, as above described, while ;the lower would simply lie along the bottom of In other cases, I may form the two surfaces by building up-on an imaginary surface traced by a straight line as above described, both surfaces approaching closely to the imaginary directing surface so formed. It will be seen, however, that if the. under s 'rface of the wing is swept out by a stra line in the manner indicated above, :a; he wing is of from the true geometrical form.- small departures from the strict 1S preferably taken through hind cone shaped wingsurface' (see Fig. 14): .The

, at about two-fifths form of. the upperthe path of the traveling line -'the skid, 6,

however, be ad- In constructing the front part of the only moderate thickness the upper surface would depart to only an immaterial extent form,I intend to include within the scope of the present invention. 1 I now describe .one'form. of monoplane by way of example fitted with the 'type 'of wing described'above' with 'refer- I Referring for this" purpose to Figs. -'13.to 16, thebody, 1,. .is v shaped like a bird,-'fish orboat and carries ence to Figs. 1 and 2.

All such geometric amotor, pilot, stores andpartof the mecha- 7 1118111 driving the propellers, 2. This body rectangular in, cross. sections thewings, 3, the lower-front part or .breast? being concave andshaped on'each side as-an extension of-the underside of the.

tips of the wings 'shouldextend behind the center 'of'gravity of the whole apparatus,

this point beiug distant froi'n'the' front endbody,- while therear end of the body should preferably be lower than the; rear tips of thewings. The body, .1, should be strongly constructed in the forward and middleipart structed in the rear part. The sides ofthe bodyare raised above the stronger portion. of .itsframework by light. the upper part is covered in preferably by. light fabric stretched across level with the left for the pilot. A single strong skid'or runner, 6,'1ies in a fore-andaft direction under the centerof the body, 1, and is'at tached'thereto by a single member, 7 and by symmetrically. disposed. pairs of rigid members, 8, sloping upward and outward from the skid, sides of the body, 1. set side by strong sides of the body are attached to or to the apicesof horizontal triangular frames projecting therefrom'and are further connected to "the strong sides of the body. by forked vertical members, 10. The wings, 3, are attached to. the body, 1, by strong boom members, 11, which. members are. preferably of I section .or of tops. of the bulwarks, 4;, a space, '5,'being A pair of wheels, 9,

fit under the cone-shaped wing surface but may be inclosed in the thickness of the wings. Cross ribs, 12, curved to fit the wing surfaceserve'to strengthen the wings,- 3, and to preserve their shape. Vertical struts, 13, are attached to the boom mem-. bars, 11, projecting above and below and connected at their upper and lower endsby' fore-and-aft members, cross-braced above and below by wires, 15. A frame is erected upon the strongsides of body, '1, consisting of the length ofthe girder-like construction, and are curved to those portions which'lie bebulwarks, 4., and

6, to the strongly built i side and directly under, the

14;,thewh0le being I "'Bowden sheaths to the pilot.

of an upright strut, 16, a double strut shaped like an inverted V, 17 and a foreand-aft solid member, 18, the whole frame beingbraced with wires, 19. Wires, 20, are connected from the outer ends of the boom members, 11, to the tops of the struts, 13,

and thenceato the tops of the struts, 16 and 17, and wires, 21, pass'also from the outer ends of the boom members, 11, to the lower 10 ends of the strut, 13, and thence to the skid, 6. Other wires, 22 and 22", pass from the .intersections of the struts, 13, with the' boom members, 11,to the tops of the struts, I 16 and 17, and to the skid, 6.

For the guidance of all machines constructed in accordance with this specification, I considerthat the controls described in the British patent specification, No. 1469 of May 21st, 1870, which comprise horizontally pivoted flaps at the rear tips of the wings, are particularly suitable. In the present invention, similar flaps or ailerons, 23,'are hinged by their front edges to the outer parts of the rear booms, 11. Ifwith such flaps it is desired to incline the frontof the machine upward the flaps would be inclined upward so a to receive air pressure upon their upper 'of the machine down. To incline the front of the machine downward the flaps would be lowered so as to receive air pressures on their under sides and so lift the rear of the machine. In order to turn to the right, the right hand flap would be raised and the left hand flap lowered; and in order to turn to the left, the left hand flap would be raised and the right hand flap lowered.

It will be observed that that portion of the rear boom, 11, which is opposite the 40 flap, 23, is part straight and part with a slight curve. In order to simplify the hinging of the flap, 23,. to the boom, 11, I slightly modify the surface at the extreme rear tip of the wing, without materially reducing its concavity, so that that part of the-rear boom, 11, which is opposite to the flap, 23, may be made straight throughout, as this can be efiected without departing from the general characteristics of the wing. This modification I may effect where necessary in all wings constructed in accordance with the present invention.

Short vertical struts, 24, intersect and are attached to the solid front edges of the flaps, 23, and their upper and lower ends are attached to the rear corners of the flaps, 23, by wires, 25. Stranded w re cords, 26, are'attached to the endsof the struts, 24, and are'led around 'a guide, 26*,and thence by any convenient arrangement of -pulleys or By pulling and slacking on these cords the flaps, 2 3, can

be raised or lowered. l

The .motor, 27, is preferably placed in 35 front of the pilot andthe propellers behind,

surfaces and so force the rearof the up the latter in this position having less effect on the stability of the machine. A shaft, 28, passing under the pilots seat low down in the body, 1, transmits the power from the motor to the propellers, 2, which are attached to the laterally projecting frame, 29', (see Fig. 16) and are driven from the shaft, 28, by chains, belts or by any convenient mechanism.

The shaft, 28, is preferably set below the '15 level of the crank case of the motor and driven therefrom bv any convenient gearing; by extending .ue shaft forward under the motor, the position of the latter can be readily changed forward or backward with- '80 out any further disturbance of the driving mechanism beyond that involved in shifting the sprocket wheel or toothed wheel at the forward end of the shaft, 28, forward or backward to correspond. a

Any of the above forms of wing are applicable to machines in which two sets of wings are superposed as well as to the monoplane type of machine above described. Of

the forms described above,.however, I consider that shown in Figs. 8, 9 and 10, the most suitable for this purpose, since en ac count of the whole of the front edge being straight and nearly all the back art being flat, straight boom members can e utilized in the construction of the wings and thus two such wings can be readily held in position one above the other by a truss system of upright struts and diagonal ties as in ordinary biplane construction. gle of incidence of the upper Wing's however, should decrease toward the tips and preferably become negative as before they lower wings may have a uniform angle of incidence or even one increasing sli htly toward the tips; if such increase excee sa comparatively moderate extent, however the stability of the aeroplane will suffer. But I consider it preferable and the best results are obtained when both pairs of wings are so constructed that while. their inner portions have a positive angle of incidence, their tips have a much sma ler or actually negative angle of incidence, the variation being greater, in the upper than in the lower pair of wings, and the superposed wings be ng so set relatively to each other that the tips er pair are inclined forward and in relation to those of the lower downwar pair.

The principles explained above in relation to a bi lane may also be applied to aero planes aving more than two superpose main supporting surfaces; in such cases it is advisable that the angle of incidence of the uppermost main supporting surface should decrease toward t e'tips and that these tips should slope downward and forward inrelation to the tips of the lowermost surface.

While the an- 100 According to the particular form of biplane shown, (see F igs. 17,18 and 19') the main supporting surfaces of the machine consistof upper and lower wings, 30, and 31, respectively, (to be referred to in detail hereinafter), inclined backward as shown and connected by the vertical struts, 32, and ties, 33, usual in biplane construction. The wings themselves may be formed with longitudinal booms, 34c, and transverse ribs, 3'5, ailerons i or flaps, 36, actuated by any suitable means 3 being hinged preferably to the booms of the upper wings. Below the lower wings is arranged aboat-shaped body, 37, rectangular in cross section and provided with a raised bulwark, 38, this body carrying a transversely disposed framework, 39, on which the propellers, 40, are mounted; as shown in Fig. 3 the rear tips of the lower wings are drooped as shown so as to be slightly below the rear end of the body.

In the particular example of my invention illustrated, the propellers are driven by chains, 41, from the motor, l2, while the position' of the pilot whose head only appears I above the bulwarks, is indicated by a. cross in Fig. 19. Below the body an arrangement of wheels, 43, is provided with an intermediate runner, to take the weight of the machine when on the ground. Vertical screens, l5, one at each end, are provided,

connecting the upper and lower wings, these tinguished by letters with a numerical ,sufhx.

The lower wings are of the same type as the upper wings, the angle of incidence of the inner ends being the same in eachcase,

' but as will be seen particularly on reference to Figs. 23 and 24, the gradual decrease of the angle of incidence toward the tips extends through a smaller range. i

The differentiation of therange of varia- "tion of the angle of incidence in the upper and lower wings of a plane I wish 'to em:

' phasizeuas one of the important features of the present invention. "92s a result of such variation it obviously which the upper-and lower wings have the samerposi-tiveangle of incidence at the inner ends and the angleof incidence" changes sign at some point of the length of the wings that the tips of the upper wing have a downward and forward inclination in relation to those of the lower wing,

{to lows in a case in,

algebraically the angle of incidence of the] fore-ancbaft cross section taken through the 'ing surface and rear flap, while-in order to make the machine descend, therear flaps would be inclined downward;- in order to turn to the right hand side, the right flap would be raisedand the left flap lowered and vice'versa to turn to the left.

According to a modification of the invention, instead of effecting the necessary set of the wings as described above, the rear edges of one or more of the wings may be given a certain degree of flexibility.

I find that with wings as described above in order to obtain ahigh degree of automatic stability itis important to preserve a proper relation between the overall length and breadth of the wings as seen in plan or in other words, between the length and breadth of a rectangle inclosing the wings.

Good stability is obtained as above stated when the rearwardly projecting wings make an angle of between 4:0?and 70 with the line of flight but as this angle is increased the stability becomes less-perfect. In such cases, therefore,'I preserve the necessary ra-- tio between length and depth as defined above by fitting a supplementary supporting surface in front of themain wings and I preferably arrange for this surface to be movably mounted so that it may act as a horizontal rudder to elevate or depress the machine. In the limit the rearward angling may decrease to zero in which case the wings are in alinement.

Finally I wish it to be understood that although I havedescribed certain examples. of my invention in considerable detail, nevertheless the principles involved may be embodied in a variety of different forms.

Having now described myinvention what I claim as new and desire to secure by Letters Patent is 1. Anaeroplane having a pair of rearwardly extending iiflectionless supporting surfaces symmetrically disposed, each of said surfaces having a pos tively inclined port-ion and a negatively inclined portion, -sa1d posit vely 1ncl1ned portlon being nearer.

lie

the center line of the aeroplane than said negatively inclined portion, as set forth.

. 2. An aeroplane having a pair of rear wardly extendlngmflectionl ess supporting surfaces symmetrically disposed, each of said surfaces having-a positively inclined center portion and a negatively inclined tip portion, as set-forth.

3. aeroplane having'a pair of rear- 'wa-rdly extending supporting surfaces symmetrically disposed, each of salt wings having a positively inclined portion and a negatively inclined portion, said positively inclined portion being nearer the center line ofthe aeroplane than'said negatively inclined portion together with an intermediate portion having a downward concavity, the axis of the concavityrunning from said positively to said negatively inclined por- .tion, as set forth. I 4. An'aeroplane having rearwardly projecting supporting surfaces formed with a downward concavity the axis of which is inclined backward at a greater angle to the line of flight than are the rearwardly projecting supporting surfaces themselves, as set forth.

5-. An aeroplane having rearwardly ex 6.-An aeroplane'having rearwardly projecting supporting surfaces concave downwvard and swept out by generatrices which are inclined backward at a greater angle to the line of flightthan are the supporting surfa'ces themselves, as set forth.

7. An aeroplane having rearwardly extending main supporting surfaces with leading and trailing edges and a portion with a downward concavity, the axis of said concavity being oblique to saidedges, as set forth.

8. An aeroplane having a plurality of superposed supporting surfaces the angle of incidence of the uppermost and lowermost of which decreases from the center toward the tips and are so set relatively to each other that the tips of said uppermostpair.

are inclined forward and downward in relation to those of said lowermost; pair, as setforth'. a

9. A biplane having upper and lower supporting surfaces the angle of incidence of said supporting surfaces bein formed as a straight outwardly running conduit, said surfaces having a positive angle of incidence at a point toward the center 'line of the aeroplane and a negative angle of incidence at a point remote therefrom, as set forth.

11. An aeroplane havin a pair of sup-.

porting surfaces, each of w ich is formed as a straight outwardly running conduit, the angles of incidence of each of said surfaces decreasing algebraically from the center to the tips, as set forth. 12. An aeroplane having supporting surfaces with leading and trailing edges, said supporting surfaces having a portion formed as a straight conduit and passing obliquely from one of said edges to the other, as set forth.

13. An aeroplane having inflectionless supporting surfaces symmetrically disposed each with a rearwardly extendin leading edge and an angle of incidence decreasing from the center outwardly, as set forth.

14. An aeroplane having developable supporting surfaces symmetrically disposed, the angle of incidence of which surfaces decreases algebraically in a direction from the center to the tips, as set forth.

15. An aeroplane having developable sup porting surfaces symmetrically disposed each of said surfaces having a positively inclined center portion and a negatively inclined tip portion, as set forth.

In testimony whereof I afiix my signature in presence of two witnesses.

Jon's WILLIAM DUXXE.

\Vitnesses:

M. C. DUNNE, A. F. BRADLEY. 

